1. High-resolution urban-scale impact of retro-reflective façade materials on building thermal loadMarko Bizjak, Domen Mongus, Niko Lukač, Jihui Yuan, 2025, original scientific article Abstract: This paper presents a high-resolution urban-scale evaluation of the impact of retro-reflective (RR)facade materials on building thermal load. Unlike earlier studies limited to isolated buildings or simplified geometries, we integrate LiDAR-derived 3D city models, local meteorological data, and per-triangle thermal load simulation to quantify seasonal thermal load impact on an urban scale. The triangle-based framework enables detailed estimation of shading, orientation, and vegetation effects under realistic urban configurations. The methodology was applied to 914 buildings in Celje, Slovenia, represented by more than seven million building surface triangles. Results show that Prism RR material increased annual heating demands by 2.1 % and reduced cooling demands by 0.76 %, while Glass bead material increased heating by 1.6 % and reduced cooling by 0.65 %. On the days of maximum city-aggregate cooling demand reduction, Prism and Glass bead materials reduced cooling demands by upto 19.31 % and 15.39 %,respectively. These location-specific results demonstrate a seasonal trade-off, where reduced summer cooling demand is counter balanced by increased heating demand. The analysis also identifies a previously underreported seasonal asymmetry, with the highest heating demand increases occurring in spring when solar irradiation is high yet heating demand remains.
Keywords: thermal load, lagre scale, retro-reflective materials, glass bead, prism
Published in DKUM: 12.12.2025; Views: 0; Downloads: 0
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2. Dynamic modeling and experimental validation of the photovoltaic/thermal systemKlemen Sredenšek, Eva Simonič, Klemen Deželak, Marko Bizjak, Niko Lukač, Sebastijan Seme, 2025, original scientific article Abstract: The aim of this paper is to present a novel and comprehensive methodology for the dynamic modeling and experimental validation of a photovoltaic/thermal system. The dynamic model is divided into thermal and electrical subsystems, encompassing the photovoltaic/ thermal module and the thermal energy storage. The thermal subsystem of both the photovoltaic/thermal module and the thermal energy storage is described by a one-dimensional dynamic model of heat transfer mechanisms and optical losses, while the electrical subsystem is presented as an electrical equivalent circuit of double diode solar cell. Model validation was conducted on a modern experimental photovoltaic/thermal system over an extended operational period at a five-minute resolution, with validation days classified as sunny, cloudy, or overcast based on weather conditions, thereby demonstrating an applied approach. The results demonstrate the lowest deviation values reported to date, confirmed using six quantitative indicators. The added value of the proposed methodology, not previously addressed in the literature, lies in the following contributions: (i) comprehensive modeling of the entire photovoltaic/thermal system, (ii) accurate consideration of optical losses in the photovoltaic/thermal module, and (iii) long-term experimental validation. Overall, the proposed methodology provides a reliable and efficient framework for PV/T system design, optimization, and long-term performance assessment.
Keywords: photovoltaic/thermal system, thermal energy storage, dynamic modeling, experimental validation, heat transfer mechanism, temperature, electrical power
Published in DKUM: 10.11.2025; Views: 0; Downloads: 10
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3. Uporaba grafovskih samokodirnikov za odkrivanje anomalij v kompleksnih mrežah : magistrsko deloNika Kramberger, 2025, master's thesis Abstract: V magistrskem delu raziskujemo uporabo grafovskih samokodirnikov za odkrivanje anomalij v kompleksnih mrežah. Najprej predstavimo temeljne pojme s področja kompleksnih mrež, grafovskih nevronskih mrež, anomalij in samokodirnikov. Nato opišemo pripravo podatkov, zasnovo modela ter postopek dodajanja atributnih in strukturnih anomalij. Poseben poudarek namenimo vlogi rekonstrukcijskih napak pri prepoznavanju anomalij, uspešnost modela pa ovrednotimo z uporabo metrike F1. Na koncu predstavimo rezultate testiranj in v zaključku povzamemo glavne ugotovitve raziskave.
Keywords: samokodirniki, anomalije, kompleksne mreže, grafovske nevronske mreže, metrika F1
Published in DKUM: 15.10.2025; Views: 0; Downloads: 10
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4. Razvoj sistema za obdelavo slik z oblačnimi storitvami : diplomsko deloMarsel Štefič, 2025, undergraduate thesis Abstract: Diplomsko delo opisuje razvoj spletne aplikacije za obdelavo slik v oblaku z uporabo tehnologij AWS in Next.js. Sistem temelji na brezstrežniški arhitekturi, kjer ključne funkcionalnosti izvajajo storitve AWS, kot so Lambda, S3, DynamoDB in ECR. Za avtentikacijo uporabnikov se uporablja Clerk, medtem ko je za obdelavo slik implementirana lastna rešitev v okolju Docker. Poseben poudarek je na večplatformski funkcionalnosti, razširljivosti in enostavni uporabi sistema, ki omogoča shranjevanje, obdelavo in prikazovanje naloženih slik na učinkovit način. V okviru testiranja je bilo ugotovljeno, da ima med parametri obdelave največji vpliv na čas obdelovanja ločljivost slik. Pri simulaciji sočasnih nalaganj se je ta čas predvidljivo povečeval s številom uporabnikov, vendar je sistem kljub obremenitvam ohranil stabilno in zanesljivo delovanje.
Keywords: spletna aplikacija, Amazon Web Service, obdelava slik
Published in DKUM: 23.09.2025; Views: 0; Downloads: 10
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5. Spletna aplikacija za rezervacijo športnih objektov z integracijo plačilnega sistema : diplomsko deloŽiga Djurovič, 2025, undergraduate thesis Abstract: Diplomsko delo obravnava razvoj sodobne spletne aplikacije za rezervacijo športnih objektov z integracijo varnega plačilnega sistema Stripe. Namen aplikacije je rešiti težave, povezane z nepreglednimi ročnimi rezervacijami, neučinkovito komunikacijo med uporabniki in upravljavci ter odsotnostjo možnosti predplačila. V delu je predstavljeno načrtovanje arhitekture sistema, oblikovanje podatkovnega modela, implementacija zaledja in uporabniškega vmesnika ter integracija plačilnega sistema. Poseben poudarek je namenjen varnosti, avtomatizaciji postopkov, preprečevanju napak in prilagodljivosti za mobilne naprave. Testiranje je potrdilo stabilno delovanje sistema pri večjem številu sočasnih uporabnikov.
Keywords: spletna aplikacija, rezervacija športnih objektov, Stripe, varno plačevanje, uporabniška izkušnja, Next.js, Tailwind CSS, PostgreSQL, Supabase, Clerk
Published in DKUM: 23.09.2025; Views: 0; Downloads: 8
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6. Razpoznava vinogradov iz podatkov LiDARŽan Tomaž Šprajc, 2025, master's thesis Abstract: Tehnologija LiDAR človeku omogoča nove načine odkrivanja svojega okolja, v katerem se skrivajo arheološki ostanki naših prednikov in namigi k optimizaciji vsakdanjika. V magistrskem delu smo raziskovali pot, ki je vodila do daljinskega zaznanja, in rešitve, ki so omogočile njeno raziskovanje. Algoritme iskanja po drevesih in gručanja smo vgradili v tri rešitve, ki so iz podatkov LiDAR, zajetih z letalnikom in letalom, poskušale razpoznati linije vinske trte. Zagoni rešitev so temeljili na cevovodu, ki je izvorne .laz datoteke vodil do ciljnih oblik. Izplene zagonov smo predstavili v okviru njihove statistične analize, s katero smo izpostavili prednosti in slabosti posamičnega pristopa.
Keywords: LiDAR, DBSCAN, RANSAC, vinogradništvo, daljinsko zaznavanje
Published in DKUM: 04.09.2025; Views: 0; Downloads: 40
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7. Razvoj platforme za upravljanje storitev avtomehanikovAnže Fric, 2025, undergraduate thesis Abstract: V diplomskem delu smo razvili platformo, ki poenostavlja usklajevanje terminov med strankami in avtomehaniki. Platformo sestavljajo mobilna aplikacija in zaledni del s serverjem in bazo. Uporablja se uveljavljen sistem avtentikacije, kar zagotavlja varno prijavo uporabnikov. Pred rezervacijo termina lahko uporabniki pregledajo ključne informacije o avtomehaniku, kot so kontaktni podatki, delovni čas in okvirne cene storitev. Dodatno imajo avtomehaniki možnost samostojnega vnosa podatkov o opravljenih servisih, kar zagotavlja celovito servisno zgodovino vozil. Vse skupaj je povezano s potisnimi sporočili, ki se pošiljajo po operacijah s termini. V zaključku dela se predstavijo še rezultati testiranja zmogljivosti.
Keywords: avtomehanik, mobilna aplikacija, React Native, Node.js, Supabase
Published in DKUM: 04.09.2025; Views: 0; Downloads: 25
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8. Primerjava metod zmanjševanja dimenzionalnosti za napovedovanje deformacij kože 3D modelovRok Sekirnik, 2025, master's thesis Abstract: V magistrski nalogi predstavimo nevronsko mrežo za napoved deformacij kože
tridimenzionalnih karakterjev. Osredotočamo se na tehnike redukcije dimenzionalnosti, kot
sta metoda glavnih komponent in samokodirnik. Primerjamo zmogljivost obeh pristopov glede
natančnosti, uporabnosti in časovne zahtevnosti ter podamo smernice za njihovo praktično
uporabo pri generiranju realistično animiranih karakterjev v filmih, računalniški grafiki in
realnočasovnih okoljih. Rezultati kažejo, da samokodirnik zagotavlja višjo kakovost napovedi
in boljše posploševanje kompleksnih deformacij, medtem ko PCA izstopa po hitrosti in
preprosti implementaciji. Ugotovitve potrjujejo, da je izbira metode odvisna od specifičnih
zahtev problema, kar omogoča prilagodljiv in učinkovit pristop za različne scenarije v računalniški grafiki.
Keywords: PCA, samokodirnik, nevronska mreža, fizikalna simulacija, deformacija mreže
Published in DKUM: 04.09.2025; Views: 0; Downloads: 15
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9. Detection and optimization of photovoltaic arrays’ tilt angles using remote sensing dataNiko Lukač, Sebastijan Seme, Klemen Sredenšek, Gorazd Štumberger, Domen Mongus, Borut Žalik, Marko Bizjak, 2025, original scientific article Abstract: Maximizing the energy output of photovoltaic (PV) systems is becoming increasingly important. Consequently, numerous approaches have been developed over the past few years that utilize remote sensing data to predict or map solar potential. However, they primarily address hypothetical scenarios, and few focus on improving existing installations. This paper presents a novel method for optimizing the tilt angles of existing PV arrays by integrating Very High Resolution (VHR) satellite imagery and airborne Light Detection and Ranging (LiDAR) data. At first, semantic segmentation of VHR imagery using a deep learning model is performed in order to detect PV modules. The segmentation is refined using a Fine Optimization Module (FOM). LiDAR data are used to construct a 2.5D grid to estimate the modules’ tilt (inclination) and aspect (orientation) angles. The modules are grouped into arrays, and tilt angles are optimized using a Simulated Annealing (SA) algorithm, which maximizes simulated solar irradiance while accounting for shadowing, direct, and anisotropic diffuse irradiances. The method was validated using PV systems in Maribor, Slovenia, achieving a 0.952 F1-score for module detection (using FT-UnetFormer with SwinTransformer backbone) and an estimated electricity production error of below 6.7%. Optimization results showed potential energy gains of up to 4.9%.
Keywords: solar energy, photovoltaics, semantic segmentation, optimization, LiDAR, VHR imagery
Published in DKUM: 22.07.2025; Views: 0; Downloads: 10
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10. Optimization-based downscaling of satellite-derived isotropic broadband albedo to high resolutionNiko Lukač, Domen Mongus, Marko Bizjak, 2025, original scientific article Abstract: In this paper, a novel method for estimating high-resolution isotropic broadband albedo is proposed, by downscaling satellite-derived albedo using an optimization approach. At first, broadband albedo is calculated from the lower-resolution multispectral satellite image using standard narrow-to-broadband (NTB) conversion, where the surfaces are considered Lambertian with isotropic reflectance. The high-resolution true orthophoto for the same location is segmented with the deep learning-based Segment Anything Model (SAM), and the resulting segments are refined with a classified digital surface model (cDSM) to exclude small transient objects. Afterwards, the remaining segments are grouped using K-means clustering, by considering orthophoto-visible (VIS) and near-infrared (NIR) bands. These segments present surfaces with similar materials and underlying reflectance properties. Next, the Differential Evolution (DE) optimization algorithm is applied to approximate albedo values to these segments so that their spatial aggregate matches the coarse-resolution satellite albedo, by proposing two novel objective functions. Extensive experiments considering different DE parameters over an 0.75 km2 large urban area in Maribor, Slovenia, have been carried out, where Sentinel-2 Level-2A NTB-derived albedo was downscaled to 1 m spatial resolution. Looking at the performed spatiospectral analysis, the proposed method achieved absolute differences of 0.09 per VIS band and below 0.18 per NIR band, in comparison to lower-resolution NTB-derived albedo. Moreover, the proposed method achieved a root mean square error (RMSE) of 0.0179 and a mean absolute percentage error (MAPE) of 4.0299% against ground truth broadband albedo annotations of characteristic materials in the given urban area. The proposed method outperformed the Enhanced Super-Resolution Generative Adversarial Networks (ESRGANs), which achieved an RMSE of 0.0285 and an MAPE of 9.2778%, and the Blind Super-Resolution Generative Adversarial Network (BSRGAN), which achieved an RMSE of 0.0341 and an MAPE of 12.3104%.
Keywords: isotropic broadband albedo, high-resolution albedo, Sentinel-2 albedo, true orthophoto, anything model, differential evolution
Published in DKUM: 23.04.2025; Views: 0; Downloads: 2
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